Patent GB-411455-A (GB)
Title: Improvements in or relating to automatic telephone systems
IPC: H04Q3/00
Filed: 1932-12-06
Abstract: 411,455. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, DIXON, R. G., 162, Westmount Road, Eltham Park, both in London, LONG, D. P., 3, Ingleby Way, Chislehurst, Kent, and PATTERSON, W. G., 59, Grove Park Road, Mottingham, London. Dec. 6, 1932, No. 34553. [Class 40 (iv).] In a system in which connections between two exchanges are routed via a third exchange if all direct junctions are busy, a registercontroller is arranged to send out normally the digits for selecting the tandem route. At the first or subsequent code selector at which the direct junctions are connected a marking switch set by a translated digit marks both direct and tandem junctions, and if a direct junction is seized a repeater associated with it sends back a signal to the register-controller to suppress the remaining tandem digits and to initiate the transmission of the numerical digits which in the case of a call to a manual CCI position will be in code. When transmission is complete, the registercontroller sends forward a booster-battery signal which may effect the insertion of a feed bridge at an outgoing relay group. In tandem calls, a single-motion switch associated with an outgoing relay-group responds to a special zone-metering digit and controls the transmission of the appropriate number of metering impulses during its complementary movement to normal. Seizure of control circuit and registercontroller ; reception of digits. The first code selector, Fig. 1, is seized over lead p and wiper DS8 if the common control circuit is idle, and relays A, B(i), C(i) operate. Relay JB removes short-circuits from all the relays K and this relay in the seized selector operates, locks over resistance YH and relay H, and connects up the control circuit. The registercontrollers accessible over the switch CF1- CF8 are arranged in four groups, each group corresponding to a pair of successive even and odd first digits 23, &c., a discriminating signal being sent to the register-controller over wiper DS7 when the digit is even. The impulses of the first digit are repeated by relay A to magnet DSM and when the second impulse arrives, relay T operates over wipers DS4, CF6, CF8. On the receipt of the fourth impulse relay T releases and latch magnet CLM operates over wiper DS6 to advance the switch CF1-CF8 to the beginning of the second group of register-controllers corresponding to first digits 45 when T again operates, and so on. At the end of the digit the relapse of C releases relay T and connects it over wiper DS5 to test for an idle registercontroller in the wanted group when relays T, HA, HB operate. Relay B, Fig. 2, in the register-controller operates over wiper CF6 and if the first digit is even relay PP(i) energizes over wipers DS7, CF1, S6, connecting up latch magnet BLM which drives the translating switch BC1-BC8 over its full-line bank to its dotted-line bank. The second digit is repeated over wiper CF2 and wiper U2 of the units register, which also acts as a digit-distributing switch, to magnet SM of the sending-switch which also acts as a B-digit register. If this second digit is greater than five, magnet CSM operates to advance the C-digit switch CS1-CS8, which also acts as the output control switch, to a second normal position on contact 12. The third digit passes to magnet CSM and during the digit relay PP, if operated, is released by a circuit through its differential winding (ii). Ground is then extended over wiper CF4 to advance the A-digit switch to a second normal position (11) in readiness for receiving the first translated digit. At the end of the C-digit, latch magnet BLM is operated over wiper U4 to advance the translating switch to a position individual to the code dialled, relay T operating over wiper S6 and one of wipers CS4-CS8 when this is reached. Relay TT also operates, connects ground over wiper CF1 to re-operate relay C, Fig. 1, and causes switches S1-S8, CS1-CS8 to return to normal, relay SS(i) then operating. The numerical digits are distributed over wiper U2 to the register magnets TH, H, TN, U, respectively. Local call. Relay SS connects ground over wipers U4, CS3, to relay IG which connects interrupter 12 to magnet SM. The interrupter 12 is also connected for this digit over wipers S3, CF4, to magnet DSM, Fig. 1, owing to the operation of relay MI. Impulses are transmitted until a stopping circuit is completed over wipers U4, CS2, BC2, S4, for relay SZ which locks temporarily over S5 and releases IG. Switch S1-S8 returns to normal, a sufficient pause between two digits being ensured by arranging that the stepping from positions 17 to 21 is effected by interrupter 12. On the relapse of relay C in the control circuit, Fig. 1, latch magnet LM operates over wiper DS6 causing the first code selector to hunt over the group of contacts marked by wiper DS2. When an idle outlet is reached, relay TA operates over wipers DS2, G1 (or G), P1 (or P), and operates TB which switches through the outgoing loop from the register-controller. When a local selector is seized at the first or a succeeding code selector, ground is connected to the test wire to short-circuit relay TA whereby ground is applied to wiper CF7 to operate relay SN. in the register-controller to initiate the re-transmission of the numerical digits, relay SN causing switch CS1 to advance to position 6. Loop impulses for all digits except the first with a make to break ratio of 1 : 2 are produced by interrupter 11, whilst the impulses for directly operating magnet DSM are produced by interrupter 12 with a ratio of 2 : 1. After the last numerical digit has been transmitted, relay CO operates over wiper CS2 and completes a circuit over wiper BC8 and a jumper to terminal b for relay JA, Fig. 1, over wiper CF1. Relay JA short-circuits resistance YH to operate switching relay H and releases HA and the register-controller. Call over direct junction. The operation of the code selector and register-controller is substantially the same as for a local call, but the contact in bank BC8 is jumpered to terminal c so that relay J operates over wiper CF3, completes a local circuit for JA and applies a booster battery BB to the outgoing test wire. This booster connection may be employed for switching in a feed at the outgoing end of the junction and is so employed for CCI and tandem calls as described in succeeding paragraphs. The repeater shown in Fig. 4 is however of the type which always contains a feed. When this repeater is seized, relays A, BD, I, B(i), J, operate and ground is applied to the c-wire to initiate the transmission of numerical impulses from the register-controller as described above. When the called party replies, relay D operates releasing BD so that DD operates and booster metering battery BB is applied to the c-wire during the release period of relay J. If a busy condition is encountered, the release of relay I in response to a busyflash signal releases BD so that on the succeeding operation of I, BR operates, sends back busyflash BF, and operates relay HA to open the outgoing circuit. Call to CCI exchange. Relay CE operates over a jumper wire to terminal a, Fig. 3, so that when ground is applied to wire p by the operation of relays N, NE in a direct-junction relay-set, Fig. 5, relay CD(i) is operated instead of SN to change over the register-controller circuits for code-impulsing. In position 1 of wiper S7, relay LS(ii) operates over the b-wire until the CCI apparatus is ready to receive Signals. Code transmission takes place in known manner when LS releases and after the units digit has been sent relays CO, J, operate and a booster impulse is sent forward over wire p to operate relay BS, Fig. 5, which inserts a feed. If a call 'to a CCI position is routed over a tandem exchange, ground is not sent back over the third wire so that CD does not operate and the numerical digits are sent out uncoded to a coder associated with the outgoing end of the final junction, a polarized relay D, Fig. 2, holding up transmission until a coder has been seized. Tandem call ; zone metering. Tandem junctions are marked over wiper DS3 and the extension of a call to a relay set, Fig. 6, associated with the outgoing end of a tandem junction proceeds as already described. In the relay set, relays B(i), A, C(i), BD, operate and the impulses of the first digit received, which is always odd and is used to determine zone metering, are repeated to magnet DM. At the end of the digit the relapse of C completes a through metallic circuit over which the remaining digits are transmitted. After the last digit, the connection of booster battery to wire p operates BS(i) which inserts the feed bridge. When the called party replies, relay D releases BD connecting magnet DM to an interrupter which steps switch DS1-DS5 to its 11th position during which at each even position it transmits a booster-battery impulse over wire p. Alternative routing. For calls to exchanges provided with alternative-routing facilities, the translated digits cause the markings over wipers DS2 and DS3 at the first or subsequent code selector of both direct and tandem junctions the switch after hunting unsuccessfully over the direct junctions passing on to search the tandem junctions. As soon as a direct junction is seized, a signal is sent to the register-controller to suppress further tandem digits. Call to operator. If the single digit 0 is dialled, the switch CF1-CF8 is not started, but magnet LM is operated over bank DS6 to hunt for an idle outlet in a group marked by wiper DS2 over terminal MB. Relay H operates over DS5 on the release of C. Busy and NU conditions. If a busy condition is encountered by the first code selector and no alternative route is available, the first code selector advances to its last terminals at which relay TA operates in series with LC(i) and TB (iii) (which is differentially wound so that TB is not energized). Busy flash BF